Asymmetric merons at room temperature: experiments and simulations

Abstract

Topological defects are a key to understanding global properties in many different condensed matter systems with long range order. Although artificial skyrmion textures (with integer topological index Q = 1) have been imprinted in multilayers, related topological defects with fractional skymionic charge Q 0 1/2 (socalled merons) have also been described and observed. Actually meron textures bound to magnetic stripe domain pattern dislocation cores have been recently observed in weak perpendicular anisotropy NdCo/Py bilayers supporting a weak stripe domain pattern at equilibrium. In this work, we have extended our previous study by performing a detailed characterization of the 3D micromagnetic structure of meron textures in GdCo/NdCo/Py trilayers. Magnetic Transmission X-Ray microscopy (MTXM) at different sample orientations has been used to obtain the magnetic configration of the bottom/top/central layers around these merons, taking advantage os its long penetration depth to study buried layers and the possibility to obtain independently elements selective images of each layer magnetization. A detailed analysis shows that most merons appear either on top or bottom layers but not on both at the same time. This asymmetric indepth configuration follows strong selection rules based on defect topological characteristics which will be outlined and discussed in terms of micromagnetic simulations.